Vehicle alternator

ABSTRACT

A vehicle alternator capable of promptly discharging water coming into the interior thereof from a water discharge hole. 
     The vehicle alternator includes a rear bracket which supports a rotary shaft driven by an engine at the rear end thereof, has a plurality of vent holes disposed thereto and is mounted so that the main surface of the rear bracket faces in a vertical direction and the rear bracket includes a water discharge hole bored in a wall surface facing to the ground and a pair of guide portions continuously extending from the opening of the water discharge hole toward the ground in confrontation with each other.

TECHNICAL FIELD

The present invention relates to a vehicle alternator having a waterdischarge structure capable of promptly discharging water coming intothe alternator.

BACKGROUND ART

A vehicle alternator mounted to the engine of a vehicle is oftensplashed with water and in particular with muddy water when it isactually used. On the other hand, a vent hole is disposed to the rearbracket as the casing of the alternator to radiate the heat generated bythe generation of power. It is preferable that the vent hole is made aslarge as possible to improve a heat radiating property. Since, however,the vent hole cannot be made large from the view point of the role ofthe rear bracket for protecting the components accommodated therein andthe necessity for securing the strength of the rear bracket itself, aplurality of the vent holes each having a proper size are disposed. Suchbeing the case, in the conventional alternator, since water such asmuddy water and the like is liable to come into it through the ventholes, the alternator is provided with a water discharge hole disposedto the lower side of the rear bracket to thereby effectively dischargewater coming into it.

FIG. 7 is a front elevational view of a rear bracket applied to aconventional alternator.

In FIG. 7, the rear bracket 1 of the alternator has a plurality of ventholes la each having a proper size and disposed thereto. A waterdischarge hole 1 b is disposed to the lower side of the rear bracket 1.The water discharge hole 1 b is formed by cutting out the wall surfaceof the terminal mounting portion 1 c of the rear bracket 1 as shown inFIG. 8.

As shown in FIG. 9, the rear bracket 1 is disposed coaxially with astator core 2 and journals a rotary shaft 3 driven by an engine 11 atthe rear end thereof. A rectifier 4 is mounted to the terminal mountingportion 1 c of the rear bracket 1.

As shown in FIG. 11, the alternator 10 arranged as described above ismounted to the engine 11 so that the main surface of the rear bracket 1faces in a vertical direction. The terminal mounting portion 1 c islocated on a lower side (ground side) and the opening of the waterdischarge hole 1 b faces downward.

When the alternator 10 is splashed with water 5 such as muddy water andthe like, the water 5 comes into the alternator 10 from the vent holes 1a. The water 5 having come into the alternator 10 flows along the insidewall surface of the rear bracket 1 and is discharged from the waterdischarge hole 1 b to the outside.

In, for example, the terminal mounting portion 1 c to which therectifier 4 is mounted, the interval between the inside wall surface ofthe rear bracket 1 and the rectifier 4 is narrowed. Thus, when the water5 comes into the terminal mounting portion 1 c arranged as describedabove, the water 5 is deposited on the rectifier 4 by surface tension asshown in FIG. 10 and difficult to be discharged from the water dischargehole lb. When the water 5 contains many types of impurities such as mudand the like, they are dried without being discharged from the waterdischarge hole 1 b and clog the water discharge hole 1 b by therepetition of the above process. When the water discharge hole 1 b isclogged, since the water 5 having come into the alternator 10 staysthere without being discharged, there is a problem that the water makesthe components accommodated in the rear bracket 1 such as the rectifier4 and the like to an unacceptable state and causes a voltage drop by thecontact of the rear bracket I serving as the ground with the components,whereby a breakdown is arisen.

DISCLOSURE OF THE INVENTION

An object of the present invention for solving the above problem is toprovide an alternator having a water discharge structure capable ofdischarging water including impurities such as mud even if the watercomes into the alternator and preventing the breakdown thereof which iscaused by that the impurities clog a water discharge hole and the waterstays in the alternator.

The vehicle alternator of the present invention includes a rear bracketwhich supports a rotary shaft driven by an engine at the rear endthereof, has a plurality of vent holes disposed thereto and is mountedso that the main surface of the rear bracket faces in a verticaldirection and the rear bracket includes a water discharge hole bored ina wall surface facing to the ground and a pair of plate-like guideportions continuously extending from the opening of the water dischargehole toward the ground in confrontation with each other so as to enlargea gap between the guide portions. The relationship between the width ofthe opening A of the water discharge hole and the extending length B ofthe guide portions is set to B≧2A.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view showing a rear bracket applied to analternator according to an embodiment 1 of the present invention;

FIG. 2 is a perspective view showing the main portion of the rearbracket applied to the alternator according to the embodiment 1 of thepresent invention;

FIG. 3 is a sectional view showing the main portion of the alternatoraccording to an embodiment 1 of the present invention;

FIG. 4 is a sectional view showing the main portion of the alternatoraccording to the embodiment 1 of the present invention for explaininghow water is discharged;

FIG. 5 is a sectional view showing the main portion of a rear bracketapplied to the alternator according to an embodiment 2 of the presentinvention;

FIG. 6 is a front elevational view showing a rear bracket applied to thealternator according to an embodiment 3 of the present invention;

FIG. 7 is a front elevational view showing a rear bracket applied to aconventional alternator;

FIG. 8 is a perspective view showing the main portion of the rearbracket applied to the conventional alternator;

FIG. 9 is a sectional view showing the main portion of the conventionalalternator;

FIG. 10 is a sectional view of the main portion of the conventionalalternator for explaining how water is discharged; and

FIG. 11 is a font elevational view showing the state that theconventional alternator is mounted to an engine.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be described belowwith reference to the drawings.

Embodiment 1

FIG. 1 is a front elevational view showing a rear bracket applied to analternator according to an embodiment 1 of the present invention, FIG. 2is a perspective view of the rear bracket when it is viewed from a lowerside, FIG. 3 is a sectional view showing the main portion of thealternator according to the embodiment 1 and FIG. 4 is a sectional viewof the main portion of the alternator according to the embodiment 1 forexplaining how water is discharged.

In FIG. 1 and FIG. 2, a rear bracket 20 has a plurality of vent holes 20a each having a proper size, a terminal mounting portion 20 b to which arectifier is mounted, a brush holder accommodating unit 20 c foraccommodating a brush holder and the like which are disposed thereto. Awater discharge hole 20 d is disposed to the side wall surface of theterminal mounting portion 20 b. Further, a pair of plate-like guideportions 20 e continuously project outward from the opening of the waterdischarge hole 20 d in confrontation with each other so as to enlarge agap between the guide portions. Note, the width of the opening A of thewater discharge hole 20 d is set to 1.5 mm and the projecting length ofthe guide portions 20 e is set to 5 mm.

In FIG. 3, the rear bracket 20 is disposed coaxially with a stator core2 and journals a rotary shaft 3 driven by an engine 11 at the rear endthereof. The rectifier 4 serving as an accommodated component is mountedto the terminal mounting portion 20 b of the rear bracket 20. Inaddition, a brush holder 6 serving as an accommodated component isaccommodated in the brush holder accommodating unit 20 c.

An alternator 21 arranged as described above is mounted to the engine 11so that the main surface of the rear bracket 20 faces in a verticaldirection. The terminal mounting portion 20 b is positioned on a lowerside, the opening of the water discharge hole 20 d faces downward andthe guide portions 20 e extend in a ground direction.

When the alternator 21 is splashed with water 5 such as muddy water andthe like, the water 5 comes into the alternator 21 through the ventholes 20 a. The water 5 having come thereinto flows along the insidewall surface of the rear bracket 20 and reaches the water discharge hole20 d. The water 5 having reached the water discharge hole 20 d entersbetween the pair of guide portions 20 e from the water discharge hole 20d by surface tension and stays to the lower portion between the pair ofguide portions 20 e which the gap therebetween is enlarged toward theground, as shown in FIG. 4. At the time, since the water 5 stays to thelower portion between the pair of guide portions 20 e, there is asufficient distance between the water 5 and the rectifier 4. Thus, whenthe amount of water 5 staying between the pair of guide portions 20 eincreases, its dead lard is more than surface tension generated betweenthe water 5 and the wall surfaces of the guide portions 20 e before itcomes into contact with the rectifier 4 and then the water 5 drops frombetween the pair of guide portions 20 e.

When the rear bracket 20 was made by variously combining the width ofthe opening A of the water discharge hole 20 d with the projectinglength B of the guide portions 20 e and how water was discharged wasobserved, it could be confirmed that the water could be particularlypromptly discharged when B≧2A. It is thinkable that the drain from theguide portions 20 e is accelerated because the dead lard of the waterstaying between the guide portions 20 e is more than surface tensiongenerated between the water and the wall surfaces of the guide portions20 e by the relationship between A and B which is set to B≧2A.

As described above, according to the embodiment 1, when the alternator21 is mounted to the engine 11, since the water discharge hole 20 d isdisposed to the side wall surface of the terminal mounting portion 20 bfacing the ground which is located to the lower side of the rear bracket20, the pair of guide portions 20 e continuously extend from the openingof the water discharge hole 20 d downward (in the direction of theground) so as to enlarge the gap therebetween, and the relationshipbetween the width of the opening A of the water discharge hole and theextending length B of the guide portions is set to B≧2A, the water 5having come into the alternator 21 is promptly discharged through thewater discharge hole 20 d and the pair of guide portions 20 e and thewater discharge hole 20 d is not clogged. As a result, the unacceptablestate of the accommodated components such as the rectifier 4 and thelike and the occurrence of a voltage drop resulting from the contact ofthe rear bracket 20 serving as the ground and the accommodatedcomponents, which would be caused when the water 5 having come into thealternator 21 stays there without being discharged, can be prevented.

Further, since the pair of the guide portions 20 e continuously projectoutward from the opening of the water discharge hole 20 d, the waterdischarge hole 20 d and the pair of guide portions 20 e can be moldedintegrally with the rear bracket 20 by casting. Therefore, the rearbracket 20 having the water discharge hole structure capable of promptlydischarging water can be made without the need of special processing.

Embodiment 2

FIG. 5 is a sectional view showing the main portion of a rear bracketapplied to the alternator according to an embodiment 2 of the presentinvention.

The embodiment 2 forms the inner peripheral edge of the opening of awater discharge hole 20 d to a taper shape. The other arrangement of theembodiment 2 is the same as that of the embodiment 1.

Water 5 having come into an alternator 21 from a vent holes 20 a flowsalong the inside wall surface of a rear bracket 20 and reaches the waterdischarge hole 20 d. The water 5 having reached the water discharge hole20 d flows between a pair of guide portions 20 e from the taperedportion 20 f of the opening of the water discharge hole 20 d and at thesame time enters between a pair of guide portions 20 e by surfacetension.

Therefore, according to the embodiment 2, since the water 5 havingreached the water discharge hole 20 d can more easily flows between theguide portions 20 e by the tapered shape of the inner peripheral edge ofthe opening of the water discharge hole 20 d, the water does not stay inthe vicinity of the water discharge hole 20 d, by which a waterdischarging property can be improved.

Embodiment 3

An embodiment 3 is applied when an alternator 21 is mounted to an engine11 so that the brush holder accommodating unit 20 c of a rear bracket 20is located to a lower side. Then, a water discharge hole 20 d isdisposed to the side wall surface, which faces to the ground, of thebrush holder accommodating unit 20 c and a pair of guide portions 20 econtinuously extend from the opening of the water discharge hole 20 d inthe direction of the ground in confrontation with each other.

Therefore, water 5 having entered from vent holes 20 a is promptlydischarged through the water discharge hole 20 d and the pair of guideportions 20 e also in the embodiment 3. Thus, the water discharge hole20 d is not clogged and an advantage similar to that of the embodiment 1can be obtained.

As described above, according to the present invention, the vehiclealternator of the present invention includes a rear bracket whichsupports a rotary shaft driven by an engine at the rear end thereof, hasa plurality of vent holes disposed thereto and is mounted so that themain surface of the rear bracket faces in a vertical direction and therear bracket includes a water discharge hole bored in a wall surfacefacing to the ground and a pair of plate-like guide portionscontinuously extending from the opening of the water discharge holetoward the ground in confrontation with each other so as to enlarge thegap between the guide portions. The relationship between the width ofthe opening A of the water discharge hole and the extending length B ofthe guide portions is set to B≧2A. Accordingly, water having come intothe alternator through the vent holes is promptly discharged to theoutside through the water discharge hole and the pair of guide portionsand the water discharge hole is not clogged. Thus, the unacceptablestate of the accommodated components and the occurrence of a voltagedrop resulting from the contact of the rear bracket serving as theground and the accommodated components, which would be caused by thewater which comes into the alternator and stays there without beingdischarged, can be prevented.

Since the water discharge hole is bored in the side wall surface of theterminal mounting portion to which the accommodated components aremounted, the intervals between the accommodated components and theinside wall surface of the rear bracket are narrow and accordingly thewater can be promptly discharged from the terminal mounting portionwhere the water is liable to stay.

Since the rectifier is mounted to the terminal mounting portion, thefailure of operation of the rectifier caused when it comes into contactwith water can be prevented.

Further, since the inner opening edge of the water discharge hole isformed to the tapered shape, a water discharging property can be moreimproved.

What is claimed is:
 1. A vehicle alternator including a rear bracketwhich supports a rotary shaft driven by an engine at a rear end of theshaft, the bracket having a plurality of vent holes disposed thereto,and is mounted so that a main surface of the rear bracket faces in avertical direction with respect to the ground, wherein the rear bracketincludes; a water discharge hole; a pair of plate-like guide portionscontinuously extending from an opening in said water discharge holetoward the ground; wherein the guide portions facing each other so as toenlarge a gap between said guide portions, and; wherein the relationshipbetween a width of the opening A of the water discharge hole and alength B of the guide portions is set to B≧2A.
 2. A vehicle alternatoraccording to claim 1, wherein an inner opening edge of said waterdischarge hole is formed to a tapered shape.